Pump



D. D. PHINNEY Oct. 5, 1965 PUMP Filed Oct. 5, 1962 ATTY'S.`

United States Patent O 3,209,701 PUMP Damon D. Phinney, Boulder, Colo.,assignor to Sundstrand Corporation, a corporation of Illinois Filed Oct.5, 1962, Ser. No. 228,649 12 Claims. (Cl. 103-173) This inventionrelates generally to pumps of the reciprocating type and moreparticularly to a cylinder block construction for such pumps providingfor lubricating of such pumps for use in pumping of lluids having poorlubricating properties.

Although in the pumping of fluids having good lubricating properties,the working parts of piston pumps, and especially the side walls of thepistons and cylinders thereof, may receive adequate lubrication from thelubricating fluid being pumped, where it is desired to pump lluidshaving poor lubricating properties, such as water, hydrazine, hydrogenperoxide, liquid gases, etc., lubrication must be applied from anothersource. ln using piston pumps such as check valved piston pumps forpumping liuids with poor lubricating properties it is sometimesdesirable to use a pump designed to reduce weight and complexity. Theprovision of a large swashplate angle in a piston pump is one designfeature which may be used to reduce the weight and complexity of thepump. However, the use of the large swashplate angle produces greaterside forces on the piston in the cylinders. Such side forces can lead togalling and wear of the piston or cylinder. It is desirable to minimizeor eliminate the effect of such side forces. It may also be desirable inother piston pumps for use in other applications to lessen such sideforces as may occur in the pumps.

It is an object of this invention to provide new and useful means forreducing side forces between piston and cylinder in a piston pump.

It is another object of this invention to provide a piston pump whereinthe pumping ends of the pistons reciprocate in a transversely movablecylinder means for reduction of side forces between piston and cylinder.

It is still another object of this invention to provide a pump forpumping non-lubricating fluids including means for adequately mountingand lubricating the non-pumping ends of the pistons and including meansfor reducing side forces between the piston and cylinder including theprovision of transverse motion of the cylinder means portion in whichthe pumping end of the piston reciprocally travels, the transversemotion being with respect to axis of the piston.

An additional object of this invention is to provide a check Valvedpiston pump for pumping non-lubricating fluids which includes astationary crosshead mounted within the housing and dividing theinterior of the housing into two separate enclosures, one containing theswashplate and the other containing the cylinder block, the pistonspassing through these crossheads from cylinder block to swashplate whichis rotatably mounted at a large swashplate angle, and to provide in sucha pump means for mounting and lubricating the pistons within thecrosshead, the lubricating means extending from the swashplate enclosurethrough the crosshead to the pistons, and to further provide in the pumpmeans for reducing side forces between the piston and cylinder and inassociation with the pumping ends of the pistons.

An additional object is to provide a pump in accordance with theforegoing objects wherein a crosshead and cylinder block are separatedfrom each other and wherein there is provided ring seal means betweeneach piston and its corresponding crosshead chamber, means for openingthe pump housing adjacent the swashplate and crosshead, means forremoving the crosshead and means for replacing ring seals which maybecome worn or otherwise bgfbl Patented @cia 5, 1965 ice renderedundesirable for use in the operation of the pump.

Other objects and advantages will become readily apparent from thefollowing detailed description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a vertical section of an embodiment of the pump of thisinvention; and

FIG. 2 illustrates an enlarged vertical section of an embodiment of apumping cylinder usable in the pump illustrated in FIG. 1.

While an illustrative embodiment of the invention is shown in thedrawings and will be described in detail herein, the invention issusceptible of embodiment in many diiierent forms, and it should beunderstood that the present disclosure is to be considered as anexemplication of the principles of the invention and is not intended tolimit the invention to the embodiment illustrated. The scope of theinvention will be pointed out in the appended claims.

Referring now to the drawings, numeral 30 designates a pump housingcomprising casings 31 and 32 which are separably joined by suitablemeans such as bolts, for example as shown at 33, threaded in thecasings. A drive shaft 34 having splines 35 for attachment to a primemover is rotatable in the housing and is splined at 39 to swashplate 21which is mounted in swashplate bearings 37 and i0 and is rotatable withshaft 34. Thrust bearing member 41 is rotatably mounted on swashplate 21by snap ring 38 and bearings 42.

A plurality of axial pistons in annular array is provided within thepump and although only piston 12 is shown in the drawings it is to beunderstood that each piston of the plurality abuts against thrustbearing member 41 at its non-pumping end and each is attended by otherelements in an environment similar to that of piston 12 as will bedescribed. Piston 12 is reciprocally mounted in a bronze sleeve orbushing 13 seated in a mounting block or crosshead l0 for the purpose ofmaintaining longitudinal alignment of the piston. A suitable lubricatingoil is contained within the housing in the chamber formed by crosshead10 and casing member 31, on the swashplate side of crosshead 1t). Thechamber may be, for example, about half full of the lubricating oil andthe lubricating oil is in communication with the swashplate. A portedannular conduit 23 surrounds piston 12 internally in sleeve 13 providinglubrication of the piston within crosshead 10 and particularly withinbushing 13. The lubricating oil is pumped into conduit 23 by rotation ofswashplate 21 which swirls the oil and causes a static pressure todevelop in the outside of the chamber containing the rotating parts.This pressure forces oil to flow radially inward wherever staticpassageways are provided. The general ilow of lubricating oil to conduit23 is indicated by the dotted lines and arrows shown at 14. Piston seal15, which is an O-ring 15a and Tellon (polytetralluoroethylene) boot15b, constitutes a seal between piston 12 and crosshead 10 preventing owof pumped lluid to the opposite or non-pumping side of crosshead 10.Piston seal 15 is carried in a seal cavity and is removable therefromfor replacement of the seal upon removal of a retainer plate 15enormally abutting the crosshead.

Crosshead 19, which is composed of stainless steel, abuts snap ring 43,retainer plate 15e abuts crosshead 10 and cylinder block 11 abutsretainer plate 15C. Springs, e.g., as shown at 11a urge cylinder block11, retainer plate 15C and crosshead 10 against snap ring 43 in casing32. Cylinder block 11 is also stainless steel but any other suitablematerial may be used in construction of the crosshead and the cylinderblock, since the design irnposes neither high strength nor wearresistance requirements on these parts. Piston 12, one of a plurality ofpistons is slidably mounted in a bore defined by crosshead 10, bushing13 and sealing means 15. Due to the angle of swashplate 21, piston 12 isside loaded with a force equal to 17.6% of the hydraulic load on thepumping end 12a of piston 12 for the design shown.

Pumping end 12a of piston 12 extends loosely into cylinder block 11 andclosely tits into pumping cylinder 16 which is carried by piston 12.Pumping cylinder 16 is positioned loosely within a recess in cylinderblock 11 and is free to move transversely to the reciprocal axis ofpiston 12. Reference numeral 17 indicates the metalto-metal seat ofpumping cylinder 16 on cylinder block 11. An alternative seat is shownin FIG. 2 wherein Telflon ring 17a, which is machined to tit and bondedto pumping cylinder 16, forms a seating surface on the pumping cylinderfor seating in block 11. Spring loaded discharge valve 25 assists inseating cylinder 16 in block 11, especially by exerting a slightclamping force against cylinder 16 during start-up of the pump.

In operation, a prime mover attached by spline 35 to shaft 34 causesrotation of swashplate 21. Rotation of the swashplate withcounterbalance 21a on the circumference or periphery thereof, causes thelubricating oil in housing 30 to be hurled against the inside wall ofthe housing and circulated for lubrication of moving parts as desired.Dotted and arrowed lines indicated at 14a in FIG. 1 show circulation oflubricating oil to such parts as the swashplate bearings. The dotted andarrowed lines indicated at 14 show circulation of lubricating oil topassage or conduit 23 for lubrication of piston 12 Within bushing 13.The force of the side load of piston 12 is taken against bushing 13 inthe crosshead and lubrication between the piston and bushing is highlydesirable.

The fluid being pumped, such as hydrazine, enters through inlet 19 toinlet chamber 24 in cylinder block 11, and is admitted through suitableintake valve 20 in piston 12 to pumping cylinder 16. Intake valving 20is a floating check valve retained in piston 12 by a snap ring. Duringthe pumping stroke of piston 12, intake valve 20 is closed by thepressure of the Huid being pumped. During the intake stroke valve 20 isopened by the pressure of intake iiuid in intake chamber 24, and piston12 is returned by the pressure of the intake fluid in the pumpingchamber, a greater pressure than that on the swashplate side ofcrosshead 10.

Pumping cylinder 16 floats in cylinder block 11 in the recess providedand is free to move transversely to the reciprocal axis of piston 12,thereby substantially reducing side forces between pumping end 12a ofthe piston and pumping cylinder 16. Piston seal serves to prevent thehydrazine at inlet pressure, e.g., 80 p.s.i., from leaking into thelubricating oil. If desired, Teon ring 17a acts as a suitable frictionreducing seat between pumping cylinder 16 and its seat in cylinder block11. Pumping cylinder 16 is clamped on its seat in the cylinder block bythe valve spring acting across discharge check valve 25 and actingagainst the end of pumping cylinder 16. More important, the pumpingcylinder 16 is urged against its seat by hydraulic force during pumping.Thus, the maximum side load on the piston pumping end 12a, where thereis little if any lubrication, is that required to slide pumping cylinder16 on its seat.

Although the operation of the device and the device itself has beenillustrated with respect to only one piston, i.e., piston 12, the pumpincludes a plurality of pistons of the same structure and attended bythe same structures, reciprocating axially in succession in theirannular array about the protracted axis of the drive shaft giving apumping action of the fluid entering inlet 19. In the pumping of thefluid, the fluid ows from inlet 19, through inlet chamber 24, throughpiston 12 and follows the route of the arrowed lines shown at 26 in thedrawing to outlet 22 where the uid is discharged from the pump. Springloaded relief valve 27 is provided to permit How of pumped fluid fromoutlet 22 to inlet chamber 24 to relieve excessive pressure.

The disclosed construction is advantageous in that the normal one piececylinder block construction is avoided without very expensive alignmentof the holes in the two blocks. The split in the block exposes thepiston seals facilitating initial assembly and replacement. Suchconstruction is further advantageous in that it permits the use ofbronze or other suitable crosshead materials for improved bearingconditions and further permits the use of hardened steel or othersuitable materials in the pumping cylinders without giving rise to theditiicult machining problem inherent in maintaining perfect alignmentbetween ditlerent materials normally finished by different machiningmethods, e.g., boring for bronze in the crosshead and grinding followedby honing for steel in the pumping cylinders. In order to further reducethe side forces of the pistons against the cylinder walls, withreference to the drawings a looser fit may be provided between pumpingcylinder 16 and piston 12 than between crosshead bushing 13 and piston12 where efficiency is not critical.

The construction of the illustrated embodiment provides for separationof the casing 31 and 32, e.g., by removal of securing bolts 33 and easeof removal of crosshead 10 by removing snap ring 43 and withdrawingcrosshead 10 from the housing. The ready removability of crosshead 1t)provides for easier replacement of worn parts and especially pistonseals, such as indicated at 15.

I claim:

1. In a swashplate-piston pump wherein pumping action is achieved byaction of an inclined swashplate driving a plurality of pistons slidablymounted in annular array in axial cylinders of the cylinder block andwherein the driving is a result of inclination of the swashplaterelative to the axis of the array of cylinders, the improvementcomprising crosshead means between said block and said swashplate, saidpistons slidably extending through said crosshead means, said crossheadmeans and pistons being adapted to contain uid lubricant on theswashplate or non-pumping side of said crosshead means and sealing meanson said crosshead to prevent lubricant from contacting the cylinders andto prevent the tluid being pumped from entering the crosshead and eachof said cylinder means being movable in said block transversely to thereciprocal piston axis responsive to side loads between piston andcylinder means and each cylinder containing the reciprocal travel of thepumping end of a piston.

2. The pump of claim 1 which includes conduit means within the crossheadmeans and extending from the nonpumping side of said crosshead means tothe outer surfaces of the pistons therein.

3. A pump for pumping non-lubricating fluids having a housing, a driveshaft, rotatably mounted through said housing, a swashplate attached toand rotatable with said drive shaft, a stationary cylinder block withinsaid housing and opposing said swashplate, a stationary crosshead acrosssaid housing between said block and said swashplate defining a blockenclosure and a separate swashplate enclosure within said housing, aplurality of cylinder means within said block, each of said cylindermeans having a pumping piston with a pumping end slidably extendingtherein, said cylinder means being movable in said block transversely tothe piston axis responsive to side loads between the piston and cylindermeans, a plurality of chambers through the crosshead, each of saidchambers aligned with one of said cylinder means, said piston extendingthrough said chambers to said swashplate, said crosshead preventing Huidow between said enclosures, means for charging a lubricant to saidswashplate enclosure, conduit means to each chamber in said crossheadfor conducting lubricant to each piston, said swashplate impellinglubricant into said conduit means, and ring seal means between eachpiston and cylinder adjacent the block enclosure and adapted to preventtlow of pumped fluid from said block enclosure to said swashplateenclosure during operation of the pump.

4. In a reciprocable piston pump, a piston mounting blocks, at least onepiston reciprocably mounted in said block, a cylinder support spacedaxially from said mounting block, a cylinder slidably receiving thepumping end of said piston and providing a pump chamber therefor, saidcylinder being mounted on said support for movement transverse to theaxis of the piston in response to side loading of the piston, thereby toreduce wear of the interengaged piston and cylinder surfaces, sealingmeans in said block for preventing entry of the pumped fluid into saidmounting block, means for reciprocating the piston through intake andexhaust strokes, intake valve means for admitting fluid to the pumpchamber during piston intake strokes, and exhaust valve means forexhausting fluid from the pump chamber during piston exhaust strokes.

5. An axial piston pump for handling uids which lack lubricatingqualities, comprising, a housing, a cylinder block mounted in thehousing, a separable crosshead mounted in the housing adjacent thecylinder block, a swashplate rotatably mounted in the housing adjacentthe crosshead, an annular series of axially disposed pistons extendingthrough the crosshead and having ends disposed to engage the swashplateand opposite ends extending loosely into the cylinder block, meansmounting the pistons in the crosshead to take substantially the entireside loading on the pistons during pump operation, a plurality ofcylinders respectively slida'ble on said opposite piston ends andproviding pump chambers therefor, said cylinders being mounted in saidcylinder block respectively for movement transverse to the associatedpiston axis thereby to reduce wear of the interengaged piston andcylinder surfaces, means for rotating the swashplate to move the pistonsthrough pump strokes, means for moving the pistons through intakestrokes, intake and exhaust valve means for successively admitting iluidto and exhausting fluid from said pump chambers as the swashplate isrotated, means for lubricating said piston mounting means in saidcrosshead, and sealing means on said crosshead for preventing the flowof lubricant to said cylinders.

6. A pump as defined in claim 5, including abutment means in saidhousing adjacent said swashplate engageable by said crosshead, andspring means bearing against the cylinder block and housing, urging thecrosshead, sealing means and cylinder block toward said abutment means.

'7. A pump as dened in claim 5, wherein said cylinders are mounted inrecesses in said cylinder block opening toward the end of said cylinderblock remote from said crosshead and axially movable therein, whereineach of said exhaust valve means comprises a check valve normallyclosing the remote end of said cylinder, and spring means acting againstsaid housing and said check valve member.

`8. In a pump of the type having a housing, a drive shaft, and aswashplate driven by the drive shaft, the improvement comprising: acylinder block mounted in said housing and spaced from one end of saidhousing thereby defining a space constituting a portion of a pump outletpassage, cylinders in said cylinder block freely movable transverselywith respect thereto and spaced from said end of said housing so that atleast a portion of one end of each of said cylinders continuouslycommunicates with said space, pistons slidable in said cylinders andengaging the swashplate to be recprocated thereby as the swashplaterotates, outlet passage means in said housing communicating with saidspace and adapted to convey Huid under discharge pressure from saidhousing, inlet means in said housing for delivering fluid to saidcylinders on piston intake strokes, outlet valve means associated witheach cylinder including a resiliently biased check valve engaging saidone end of each of said cylinders for urging the other ends of thecylinders into sealing engagement with the cylinder block so that thecheck valves maintain the cylinders in position during the initialrotation of the pump, and thereafter discharge uid in the spacemaintains the cylinders in position thereby permitting transversemovement of the cylinders and eliminating side loads thereon.

9. In a pump as defined in claim 8 and further including, a ring mountedon said other end of each of said cylinders having a low co-eicient offriction compared to the cylinders and engaging said cylinder block tofacilitate the transverse movement of said cylinders.

10. In a pump as defined in claim 8 and further including a crossheadhaving a plurality of axial cylindrical chambers for receiving saidpistons, said crosshead being ixedly mounted in said housing to absorbthe radical loads from the pistons.

11. In a pump as defined in claim 10 wherein said `crosshead and saidcylinder block are separable, and further including ring seal meansaround each piston mounted in the respective crosshead chambers,removable closure means for opening said housing adjacent the swashplateand crosshead, means removably mounting the crosshead in said housing tofacilitate the replacing of said seal means.

12. In a pump as dened in claim 10, and further including means in saidcrosshead for supplying lubricating fluid to each of the pistons.

References Cited by the Examiner UNITED STATES PATENTS 1,274,391 8/18Davis 103-162 2,238,252 4/41 Davis 103-173 2,374,595 4/ 45 Franz 103-1732,433,222 12/47 Huber 103-173 2,669,185 2/54 Tallis 103-173 2,797,6477/57 Floraday 103-173 3,018,737 1/62 Cook et al 103-173 3,067,694 12/ 62Fancher 103-173 3,090,313 5/63 Budzich 103-173 3,160,102 12/64 Budzich103-173 FOREIGN PATENTS 830,959 3/60 Great Britain.

LAURENCE V. EFNER, Primary Examiner. JOSEPH H, BRANSON, JR., Examiner,

1. IN A SWASHPLATE-PISTON PUMP WHEREIN PUMPING ACTION IS ACHIEVED BYACTION OF AN INCLINED SWASHPLATE DRIVING A PLURALITY OF PISTONS SLIDABLYMOUNTED IN ANNULAR ARRAY IN AXIAL CYLINDERS OF THE CYLINDER BLOCK ANDWHEREIN THE DRIVING IS A RESULT OF INCLINATION OF THE SWASHPLATERELATIVE TO THE AXIS OF THE ARRAY OF CYLINDERS, THE IMPROVEMENTCOMPRISING CROSSHEAD MEANS BETWEEN SAID BLOCK AND SAID SWASHPLATE, SAIDPISTONS SLIDABLY EXTENDING THROUGH SAID CROSSHEAD MEANS, SAID CROSSHEADS MEANS AND PISTONS BEING ADAPTED TO CONTAINE FLUID LUBRICANT ON THESWASHPLATE OR NON-PUMPING SIDE OF SAID CROSS HEAD MEANS AND SEALINGMEANS ON SAID CROSSHEAD T PREVENT LUBRICANT FROM CONTACTING THECYLINDERS AND TO PREVENT THE FLUID BEING PUMPED FROM ENTERING THECROSSHEAD AND EACH OF SAID CYLINDER MEANS BEING MOVABLE IN SAID BLOCKTRANSVERSELY TO THE RECIPROCAL PISTON AXIS RESPONSIVE TO SIDE LOADSBETWEEN PISTON AND CYLINDER MEANS AND EACH CYLINDER CONTAINING THERECIPROCAL TRAVEL OF THE PUMPING END OF A PISTON.